The invention relates to a countersteering rear axle that is intended for a vehicle and that under the influence of a lateral force on the wheel that is on the outside in a curve and that is mounted on a wheel carrier induces a rotational motion of this wheel carrier about a virtual spread axis in the toe-in direction. In this case the wheel carrier is supported on an axle body, which extends essentially in the longitudinal direction of the vehicle, by way of at least one support member formed from sheet metal. With respect to the relevant prior art reference is made, by way of example, to DD 281 154 A5 and DE 103 21 877 B4.
It is known that simple rear axles of vehicles, in particular the twist beam type axle and also the longitudinal trailing arm type axle and the diagonal trailing arm type axle, can exhibit an oversteering tendency under the influence of a lateral force. Furthermore, the aforementioned prior art already discloses remedial measures for such a lateral force influence. For example, DE 103 21 877 B4 shows a wheel carrier mounting comprising a so-called oscillating plate, in which four elastic pivot bearings are integrated. With this extremely complicated construction the wheel is steered in the toe-in direction under the influence of a lateral force. The same results are obtained in the case of the so-called countersteering rear axle that is disclosed in DD 281 154 A5, but with a considerably simpler design. However, the structural durability of its disk-shaped suspension element, which bears the wheel carrier, leaves much to be desired.
Therefore, the object of the present invention is to provide a relatively simple to build so-called countersteering rear axle which, under the influence of a lateral force on a wheel that is on the outside in a curve and which is mounted on a wheel carrier, induces a rotational motion of this wheel carrier about a virtual spread axis in the toe-in direction. The wheel carrier is supported on an axle body, which extends essentially in the longitudinal direction of the vehicle, by way of at least one support member formed from sheet metal. In this case, the countersteering rear axle satisfies the general strength requirements of vehicle axles (for example, for passenger vehicles).
This and other objects are achieved in that the support member exhibits a section, which extends essentially parallel to the plane of the wheel carrier, and a section, which is connected, when viewed in the direction of travel, to the former section behind the wheel center point and extends essentially in the transverse direction of the vehicle, and which in a lateral projection is inclined in relation to the vertical direction in essentially much the same way as the virtual spread axis. This support member is supported at least on the free ends of a sheet metal support plate, which in a lateral projection is approximately U-shaped and which, in turn, is mounted on the axle body.
Working on this basis, the invention proposes a particular support structure for the wheel carrier in the form of the herein so-called support member, which, on the one hand, exhibits enough rigidity and strength to be able to guide precisely with respect to the wheel camber the wheel or, more particularly, the wheel carrier, over the entire service life of the vehicle. The support member, on the other hand, exhibits a flexible region, which defines the desired spread axis. In this context the support member of the invention exhibits in essence two sections, which describe different planes and which are connected together by way of an edge or the like, about which these two sections can be slightly swivelled in relation to each other, so that this edge forms at least approximately or partially the spread axis (also called the steering axis). Therefore, in over-exaggerated terms, the two sections of the support member can be folded about this edge (or rather about the spread axis), in order to achieve the desired toe-in of the wheel under the influence of a lateral force. To this end, the well-known prior art provides that the spread axis has to tilt, as seen in a lateral view, in relation to the vertical plane in such a manner that the latter intersects, as viewed in the direction of travel, the wheel contact plane behind the wheel contact point.
This support member is mounted and/or supported on the axle body at least by way of the sheet metal support plate, which in a lateral view, that is, as viewed in the transverse direction of the vehicle, is approximately U-shaped. To this end, at least the free ends of both legs of the sheet metal support plate, of which the first lies, as viewed in the vertical direction, above the center point of the vehicle, and the second lies below the center point of the vehicle, preferably connected flush fitting with the support member. Preferably, the center region of the support member is connected flush fitting with the axle body, preferably with its free end. Such a configured support member can satisfy the structural durability requirements and is considerably simpler in design than, for example, the arrangement with the four elastic pivot bearings disclosed in DE 103 21 877 B4, which was discussed above.
In order to enhance the rigidity of the support member with the exception of that area of the support member that lies laterally of the spread axis and is, therefore, slightly deformable, the section, which extends in essence parallel to the plane of the wheel carrier, is connected above and/or below the center point of the wheel to another so-called web section, which extends essentially in the transverse direction of the vehicle and which is also connected to the aforementioned section, which extends essentially in the transverse direction of the vehicle and is inclined, like the spread axis, in relation to the vertical plane. This web section lies in a third, essentially horizontal plane, whereas the additional section, which is inclined like the spread axis, can be regarded more as vertically oriented, even though inclined in relation to the vertical plane. The section of the support member that is aligned essentially parallel to the wheel carrier extends essentially in the vertical direction and in the longitudinal direction of the vehicle.
The web section and/or the additional web sections give the support member the shape of a quasi-strut or the like, which is quite evident from the accompanying figures of one embodiment to be explained below.
Similarly, in order to enhance the rigidity of the support member with the exception of the area of the support member that lies laterally of the spread axis and, is, therefore, slightly deformable, a sheet metal reinforcement plate can be provided above the center point of the wheel and/or below the center point of the wheel. The sheet metal reinforcement plate supports the (respective) support member and the sheet metal support plate on the axle body. Preferably, the and/or each sheet metal reinforcement plate is connected flush fitting with the other components, that is, with the axle body and the support member and the sheet metal support plate. Preferably, the end of the respective sheet metal reinforcement plate that faces the support member extends parallel to the desired spread axis, because the contour of the plate can be defined (where such sheet metal reinforcement plates are provided) essentially by its ends facing the support member and/or by the transition regions between the sheet metal reinforcement plates and the support member.
In this context it is possible to describe a continuous upper support region of the support member, in which the upper sheet metal reinforcement plate with its end, which lies opposite the axle body, and the sheet metal support plate are supported, and in an analogous manner of a lower support region of the support member, in which the lower sheet metal reinforcement plate with its end, which lies opposite the axle body, and the sheet metal support plate are supported on the support member. The desired virtual spread axis runs through these two support regions, because these two support regions are in themselves extremely rigid, whereas their environment with respect to the two support regions has a certain degree of flexibility. Thus, this environment, which is formed essentially, on the one hand, by the section of the support member that extends parallel to the wheel carrier and, on the other hand, by the section of the support member that extends essentially in the transverse direction of the vehicle and that is inclined slightly in relation to the vertical plane, can be slightly deformed in relation to the support regions. As a result, the conditions required for the desired pivotability of the first of these two sections in relation to the second of these two sections about the spread axis that extends through the two support regions are met.
If, in the context of an advantageous further development, the upper support region lies, as viewed in the transverse direction of the vehicle, in considerably closer proximity to the center of the vehicle or the axle than the lower support region, then the virtual spread axis, defined by the upper and the lower support region, is inclined, as viewed in the longitudinal direction of the vehicle, in relation to the vertical plane in such a manner that a negative steering roll radius with its advantages that are known to the person skilled in the art can be formed. In particular, during braking operations and, thus, under the influence of a longitudinal force, such a negative steering roll radius can also produce a desired toe-in of the wheel, that is, that the wheel or rather the wheel carrier can be pivoted about the virtual spread axis in the toe-in direction.
In order to be able to generate the desired flexibility or elasticity in the support member, it may also be necessary to provide in certain regions one or more recess(es) in some regions of the support member and/or in one or more section(s) of the same.
In addition to the above-described support finally on the axle body, the wheel carrier can be supported away from the spread axis directly or indirectly by means of at least one additional connecting element, which exhibits a certain degree of flexibility, but preferably once again on the axle body. This flexibility permits the wheel carrier the desired pivot motion about the virtual spread axis. In this case, the connecting element can have an effect on the intensity of this pivot motion and, in particular, can also damp this motion. An example of such a connecting element can be a soft rubber bearing in the axial direction, said axial direction extending tangentially to the direction of rotation of the wheel carrier and the virtual spread axis.
As a consequence, the torsional flexibility about the spread axis can be adjusted and, thus, also the elastokinematic toe-in behavior of the axle. As stated above, such a connecting element exhibiting such a degree of flexibility can damp, in particular, the torsional oscillations about the virtual spread axis and additionally reduce the axle windup during braking operations. In addition, such a connecting element can transfer forces during wheel compression. At this point, the toe setting of the axle can also take place. Once again, reference is made explicitly to the fact that it is not absolutely necessary to use a rubber bearing as such a connecting element, but rather this connecting element can also be formed by a suitable structural component, which exhibits the “flexibility” in the above-described direction. Moreover, this connecting element can be provided preferably between the axle body and the section of the support member that is aligned parallel to the wheel carrier and which can exhibit a suitable extension for this purpose.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings.